Photo: Rischgitz Collection, 



SIR HUMPHRY DAVY (1778-1829). 



An illustrious chemist. Professor at the Royal Institution, 

 London, where Faraday was his assistant. His early recogni- 

 tion of "the chemical agencies of electricity" (1806) was of 

 great importance. He discovered potassium, sodium, barium, 

 strontium, calcium, and magnesium. Everyone knows of his 

 invention of a miner's safety-lamp, which has saved many lives. 



Photo: Rischgitz Collection. 



JUSTUS VON LIEBIG (1803-1873). 



One of the greatest of chemists, famous for his foundation of 

 Agricultural Chemistry , his contributions to Animal Physiology, 

 and his discoveries in Organic Chemistry. He made clear the 

 general idea of the Circulation of Matter. He had a strong 

 practical sense, and everyone knows Liebig's "beef -extract." 

 He did a great deal towards the technical equipment of chemi- 

 cal laboratories. 



